Compare Data Domain

Content Addressed Storage (CAS)

While most disk-based archiving is simply file storage on basic, SATA/RAID disk storage*, some specialty products have emerged that offer more boutique forms of Content Addressed Storage for archiving support. These systems offer additional steps to verify that objects are stored 'immutably.' But while they have in many cases created interesting levels of resilience, they trade off generality and performance.

• Archive applications only. A CAS interface can often support specific archiving applications, but it cannot support most backup software, which usually works only with tape protocols (a la VTL) or fileserver / NAS protocols.
• Too slow for backup/restore. Separately, because these systems were designed to compete with optical disks, which are notoriously slow, speed has never been a design goal. So they cannot support conventional backups or backup windows.

Data Domain systems can support most archiving applications, through its fileserver / NAS interfaces. According to Enterprise Strategy Group*, about 80% of archive customers do not require the immutability guarantees that CAS systems strive for. For these customers, mothballing files or email, online access and cost management, e.g. through deduplication, with good resilience (see Data Invulnerability Architecture), and the ability to backup data to a common infrastructure to consolidate nearline application support, is what is required.